Polar bears in two High Arctic populations seem to be doing better than scientists had thought.

The first major study of the Baffin Bay and Kane Basin populations in about 20 years has found more bears than population models predicted.

But the three-year study, done for the Canada-Greenland Joint Commission on Polar Bear, warned that the body condition of the animals in the larger Baffin Bay group is deteriorating as sea ice shrinks. It also found female bears are spending less time in maternity dens and the survival of newborn cubs is dropping.

"Body condition in the Baffin Bay polar bears declined in close association with the duration of the ice-free period," the report says.

The Kane Basin population, however, may actually be increasing.

The study updates the last report into the two populations done in 1997. Since that time, scientists have used population models to predict the health of the two groups.

Both were considered to be in decline. The Baffin Bay bears were thought to have decreased to about 1,600 from 2,173 two decades ago.

Those models seem to have been too pessimistic, partly because the earlier population survey was an underestimate. The new report says there are 2,826 bears in the Baffin region.

The report cautions that differences in survey methods mean the 1997 numbers aren't directly comparable with the latest results.

"It is not possible to conclude that the estimate of total abundance in the 2010s represents an increase."

It also warns about the health of the Baffin Bay bears.

Summer sea ice in those waters has shrunk dramatically. That's forcing the bears to spend up to a month more on land than they used to, which cuts them off for a longer period from their favourite diet of fat-rich seals.

The overall body condition of the bears has declined as a result, the study says.

As well, pregnant females are spending a month less in their maternity dens. The study found fewer bear cubs are making it past their first year.

The report has better news on the Kane Basin numbers. "(There's) relatively strong evidence for stable to increasing population."

The report counts 357 bears in that area, up from 224. Nor does that group seem to suffer from the problems dogging the Baffin Bay bears — although it's noted that Kane Basin is changing from an area of year-round to seasonal ice.

The report was commissioned in part to provide recommendations to wildlife managers on appropriate hunting quotas. However, its authors declined to offer advice on how many bears can be sustainably harvested.

The authors, an international group of polar bear experts, say they weren't given enough information on management objectives for the bears, commitments on the frequency of future monitoring, or how much risk managers are willing to assume.